This invention relates to samplers for sampling the flow of liquid in a pipe or drain and it has one important application to the sampling of effluent either because that effluent may contain a valuable product or because it may involve a pollution hazard.
In general, process pipes or drains may carry products at widely differing rates. In order to account for and measure such products a representative sample having a volume proportional to flow is required for analysis. Devices for taking such samples are referred to as liquid flow proportional samplers and two such devices are described in a report numbered TRG 2163 D by W Jennison and available from HM Stationery Office. The present invention is an improvement of a capacitative probe device disclosed in said report.